More than two decades ago scientists discovered the Arp2/3 complex, an actin (cellular protein) cytoskeketal nucleator which plays a crucial role in cell division, immune response, neurodevelopment other biological processes. But there has been no determined structure of the activated state of the complex until now, an achievement that may lay the foundation for uncovering its role in biology and in the development of disease. Researchers at Stony Brook University led by Saikat Chowdhury, Ph.D., determined the structure of Arp2/3 and describe it in a paper published in Nature Structural and Molecular Biology.